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41 Cards in this Set
- Front
- Back
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What are the advantages of light microscopes? |
-Cheap -Easy to use -Portable -Can study whole living specimens |
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What is the magnification of optical microscopes? |
X1500 |
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What is the definition of resolution? |
The ability of a microscope to produce an image that shows fine detail clearly (The clarity of an image) |
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What is the wavelength range of visible light? |
400-700 nm |
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What are laser scanning microscopes also known as? |
Confocal |
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What are laser scanning microscopes used for? |
-Biological research -Medicine |
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How do laser scanning microscopes work? |
Scan an object point by point and assemble information into an image on a computer |
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What microscope has depth selectivity? |
Laser scanning |
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Are the resolution and contrast of a laser scanning microscope high or low? |
High |
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How do transmission electron microscopes work? |
-Specimen is chemically fixed and dehydrated -Beams of electrons pass through specimen -Forms a 2D black and white image |
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What is the magnification of transmission electron microscopes? |
X2 million |
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How do scanning electron microscopes work? |
-Specimen is placed in a vacuum and coated in metal -Electrons bounce off surface of specimen and are focused on a screen -Produces a 3D image, black and white but can be given false colour |
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What is the magnification of scanning electron microscopes? |
Up to X200000 |
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What are the disadvantages of electron microscopes? |
-Large/expensive -Need training to use one -Specimens have to be dead |
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Name a substance that leaves the nucleus through nuclear pores |
RNA |
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Name a substance that enters the nucleus through nuclear pores |
Steroid hormones |
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What is the name of the double membrane surrounding the nucleus? |
Nuclear envelope |
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What is contained in the nucleolus? |
RNA |
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What are made in the nucleolus? |
Ribosomes |
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What is the name of the genetic material consisting of DNA wound around histone proteins? |
Chromatin |
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Name the four main functions of the nucleus |
-Control centre -Stores genome -Transmits genetic information -Provides instructions for protein synthesis |
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Describe the structure of the RER |
-System of membranes containing fluid-filled cavities that are continuous with the nuclear membrane -Coated in ribosomes |
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What is the name of the fluid-filled cavities in the RER and SER? |
Cisternae |
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Describe the structure of the SER |
-System of membranes containing fluid-filled cavities that are continuous with the nuclear membrane -No ribosomes on the surface |
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What are the functions of the RER? |
-Intracellular transport system, cisternae form channels -Large surface area for ribosomes |
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What are the functions of the SER? |
-Contains enzymes that catalyse lipid metabolism reactions (eg synthesis of cholesterol) -Involved with absorption/transport/synthesis of lipids |
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Describe the structure of the Golgi apparatus |
Stack of membrane-bound flattened sacs |
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What are the functions of the Golgi apparatus? |
-Modifies proteins (folds into their 3D shape, adds sugar molecules to form glycoproteins) |
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What do vesicles do at the Golgi apparatus? |
Have proteins packaged in them, are pinched off, then stored in cell or move to the plasma membrane to be exported |
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Describe the structure of mitochondria |
-2-5um -Spherical/rod-shaped/branched -Surrounded by two membranes, inner membrane is folded into cristae -Inner part is a fluid-filled matrix |
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What are the functions of mitochondria? |
-Site of ATP production -Self replicating (more can be made if cell's energy needs to increase) -Abundant in cells where a lot of metabolic activity takes place |
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Describe the structure of chloroplasts |
-Large organelles (4-10um) -Surrounded by a double membrane -Inner membrane is continuous with stacks of flattened membrane sacs called thylakoids (contain chlorophyll) -Piles of thylakoids=grana -Contains loops of DNA and starch grains |
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What are the functions of chloroplasts? |
-Site of photosynthesis -Light energy trapped and used to make ATP in grana -Abundant in leaf cells (palisade mesophyll layer) |
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Describe the structure of vacuoles |
Surrounded by a membrane called the tonoplast, contains fluid |
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What are the functions of vacuoles? |
Filled with water, maintains cell stability and makes cell turgid |
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Describe the structure of lysosomes |
-Small bags formed from Golgi apparatus -Contain powerful hydrolytic enzymes -Abundant in phagocytic cells |
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What do lysosomes do in phagocytic cells? |
Ingest and digest invading pathogens |
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What are the functions of lysosomes? |
-Keep the hydrolytic enzymes separate from the rest of the cell -Can engulf old organelles/foreign matter and digest them |
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What is the only human cell to have an undulipodium? |
Spermatozoon |
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What are cilia/undulipodia? |
-Protrusions from the cell that are surrounded by the cell surface membrane -Contain microtubules -Formed from centrioles |
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What are the functions of cilia/undulipodia? |
-Cilia in airway move mucus -Nearly all cells have one cilium that acts as an antenna -Undulipodium allows spermatozoon to move |
